Circuit breaker



May 16, 1933. s GRADY 1,909,174

CIRCUIT BREAKER 'Patented May 16, 1933 UNITED STTE STEPHEN S. GRADY, F

Parar oFF-'rca MAG-NLIA, NORTH CAROLINA., ASSIGNOR T0 FUSOID ELECTRIC CO., INC., A @EPURATION 0F NEW' YORK CIRCUIT BREAKER Application led 'March 21, '1923. Serial No. 263,414.

' the arrangement of a pair of contacts operated by electro-magnetic means responsive'to heavy over-loads in the circuit toshortcircuit the thermostat and prevent burning out of the thermostat when heavy over-loads pass through the circuit.

@ther objects and advantages will become apparent'as the description proceeds. 4

While a preferred form of the invention has been disclosed for purposes oi illustration, it should be understood'that various changes may be made in the structure withw out'departing from the spirit and scope of the invention as hereinafter set 'forth and claimed.

In the drawings: n

Fig. 1 is a plan view of the circuit breaker.

Fig. 2is an end elevation looking from the right side of Fig. 1. 4

Fig. 3 is 'a section on line 3 3 of Fig. 1.

Fig. 4 is a section on line 4-4 ot Fig. 3.

Fig. 5 is a sectionl corresponding to Fig. 3 but showing the parts in a diilerent position.

Fig. 6 is an exploded view showing details of the operating mechanism.

Fig. 7 is a diagram showing the wiring arrangements.

Fig. 8 is a detail View of amodiiication.

Fig. 9 shows the parts of Figure 8 in another position. Fig. 10 is a section on line 10-1() of Figure 8.

Fig. 11 is a section on line 11-11 of Figure 9.

Fig. 12 is a view similar to Figure 10 but showing a further modification.

Fig. 13 is a diagram of a modified system 4oi" wiring. f

Fig. 14 is a diagram showing a method of thermostat control.

Fig. 15 is a diagram showing parts of Figure 14.

Referring to the drawings more particula-rly, the device comprises a body 10, formed of porcelain or other insulating material. A terminal conductor 11 has a Contact arm 12 extending through an opening in a artition l carried by the body, and a bin ing post 13 serves to attach the wire 14 to the conductor 11. A second contact arm is loosely pivoted at 16 and has a flat face 17 normally biased toward the contact arm 12 by the spring 18. The Contact arm 15 is electrically connected with the binding post 19 from which the wire 20 leads to an appliance utilizing the current. Vlhen contacts 12 and 17 are in engagement, current is iowing to the appiiance, and the invention includes means for breaking thecircuit by separating the contacts 12 and 17.

This structure includes a sector shaped interposer 21 formed of fiber or other suitable insulating material, which is swingingly mounted on a shaft 22 supported from the body by suitable brackets. When the circuit is closed the interpcser is held inthe position of Figs. 3 and 4, and after the mechanism has been operated to interrupt the circuit the-interposer occupies a position between the contacts 12 and 17, as illustrated inFigs. 5 and 7.

The operating mechanism includes a handle member 23, the lower end of which is formed with an aperture 24 by which it is pivoted on shaft 22, and the part extending below the shaft is :formed with a notch 25 which cooperates with upper end of a bolt 26 (Fig. 3) to limitthe movement of the handle.

The handle member carries a detent 27 which projects toward theinterposer and has a straight lower side 28 and a curved outer side 29.

Another element of the operating mechanism is the latch arm 30, shown in' Fig. 6, which is formed with an aperture 31 by which it is pivoted on shaft 22 between the interposer and the handle 23 in a manner permitting free lateral movement of' the arm. Openings 32* and 33 are formed through the l oneo arm for purposes that will shortly a pear, and the free end of the arm is surroun ed by insulation 34. p

The interposer 21 has an aperture 35 formed therethrough, and a coupler 36, which is pivoted on shaft 22 between the interposer and the latch arm, has one branch 37 extending into the aperture 35 of the interposer, and another branch 38 extending into the aperture 33 of the latch arm 30. coil spring 39 is wound around shaft 22 and has its ends engaging the body 10, while its other end contacts with the end of'branch 37 and tends to bias the interposer toward the position of Fig. 5. A second coil spring 40 surrounds the shaft 22 and engages the upper side of the latch arm to press it downward, the spring 39 alone and at least with the spring provide an urging force of sufficient tension to overcome the lag or reluctance of emergency currents to insure the actuation of the interposer into circuit breaking position whenever the latch arm 30 is Xpsegring catch 41 holds theL latch arm in raised position, and the invention provides several distinct ways of moving the free end of the latch arm upwardly (looking at Fig. 1)

f to disengage it from the catch, as will now be explained.

When the parts are in the position of Fig. 3 the detent 27 is engaged in the aperture 32, as will be clear from Figs. 1 and 3. If at any time it is desired to break the circuit manually, the handle 23 is moved toward the right, as indicated by the arrow in Fig. 3. During this movement the detent 27 rides upwardly out of the opening 32, and in doing so the curved edge 29 presses the left end of latch arm 30 downwardly (Fig. 1) thereby swinging the latch arm about the fulcrum indicated in Fig. 7 and thereby causing the free end of the latch arm to ride upwardly disengaging the branch 38 of the coupler from the aperture 33 of the latch arm and causing the latch arm to move off the catch 41. As soon as the coupler arm is disengaged from the latch arm the spring 39 snaps the interposer between the contacts 12 and 17 to the position of Figs. 5 and 7. During this separating movement the contact 17, due to its loose pivotal mounting, remains parallel to the contact 12, and the interposer wipes the entire face of each contact. When in the position of Fig. 5 the interposer 21 -covers entirely the opening in the partition 1 0"L through which the contact 12 projects and snugly engages the partition 10al so that the gap between the two contacts will be effectually obstructedby the partition 10a and the interposer 21, and the spark can under no circumstances pass from one contact to the other.

When the circuit is to be aga-in closed, the circuit breaker is reset by moving the handle 23 back toward the position of Fig. 3. During thismovement the lower face 28 of the detent 27 reengages the aperture 32 to move the latch arm until its nose latches over the catch 41 again.

The invention also includes electrically operated means for tripping the latch arm 30 and breaking the circuit. For this purpose there is provided a U-shaped thermostatic element 42 which has its legs secured to the body 10 by binding osts 43 and 44, and which projects upwar 1y between the interposer and the latch arm 30 (see Fig. 2). The binding post 44 is connected with the contact arm 17 by the wire 45, and the Wire 46 runs from the binding post 43, forms the magneticoil 47, and then connects with the binding post 48 carried by the conductor 49. A binding post 50 secures the wire 20, which, as stated previously, leads to the ap liance utilizing the current.

'lihe current normallypasses through the thermostat 42, and whenever there is a light overload, the thermostat becomes heated, and due to its structure the upper end bends upwardly (Fig. 1) and disengages the latch arm 30 from the coupler 36, causing operation of the interposer as before described.

The structure of the thermostat is such that it can stand severe overloads for only a short time, and arrangement is therefore made for automatically cutting-out the thermostat and operating the circuit breaker by magnetic means whenever a heavy overload occurs.

This is accomplished through the electromagnet formed by the coil 47. The laminated core 51 of the electromagnet lies opposite a gap 52 in the insulation 34 on latch arm 30 when the parts are in the set position of Figs. 1 and 3. The normal current of the circuit passes through the electro-magnet without causing it to function, and similarly a light overload Such as causes the thermostat 42 to bend is not strong enough to vcause operation of the latch arm 30 by the electro-magnet. But when a severe overload passes through the circuit the electromagnet is powerfully energized and attracts the latch arm, permitting the spring 39 to move the interposer as before explained. The

thermostat 42 can stand the heavy overload for a short time, but it would be burned out if the heavy current passedthrough it for the full interval during which the mechanism is operating to break the circuit.

In order to prevent this result arrangement is made to short-circuit the thermostat by the first surge of the overload that puts the electro-magnet into operation. purpose a pair of contacts 53 and 54 are provided. These contacts are attached to binding posts 43 and 44 respectively, and extend up to a point where they will be in the path of the latch arm 30 as'it moves under the For this I influence of the electromagnet. With this arrangement the `energiz'ation of the electromagnet moves the latch arm to close the contacts 53 and 54, thereby short-circuiting the thermostat, and simultaneously initiates the l responsive to a heavy overload, as by a separate electro-magnet placed in the circuit.`

Various alternative arrangements of the-- contacts may be used, as will be clear from Figs. 8 to 12 inclusive. In the modification shown in Figs. 8 to 11 the contacts 55 and 56 are mounted directly on opposite sides of the swinging member 21. The contact 55 is connected by the flexible pig-tail 57 with the binding post 58, from whence leads the conductor 14, while the conductor 45, heretofore'described, is attached to the contact 56. The contacts 55 and 56 are of spring material and are formed with flat faces adapted for mutual surface engagement beyond the edge of the member 21 as shown in Fig. 11, and the outer edges of the contacts are flared to form a V-shaped notch. A stationary separator 59 is of insulating material and is stationarily mounted on the base in direct alinement with the member 21. The forward edge of separator is pointed as at 60 to facilitate entrance of the separator into the V-shaped notch to separatej the contacts as the member 21 moves from the closedcircuit position of Figs. 9 and 11 to the opencircuit position of Figs. 8 and 12.

In the modification of Fig. 12 the contact 61 is similar to the contact 56, just described,`

and is mounted on' the movable member 21, while the contact 62 is stationary. In this case the parts are so designed that the movement of member l21 carries the contact 61 from the open position of Fig. 12 to a closed position in which the contact 61 engages contact 62.

Fig. 13 illustrates a modified system of wiring in which the current does not pass directly through the thermostat 422, but passes through a coil 63 arranged so that it is insulated froxn the thermostat but is in a position to heat the thermostat.

In Figs. 14 and 15 an arrangement is shown for compensating for the dierence in temperature due to summer weather so that the thermostat will operate to break the circuit under a certain definite amount or overload at either ordinary temperatures or the elevated temperatures of summer weather. Since the raised summer temperatures wilt have some heating effect on the thermostat, provision is made to proportionately reduce the heating eflrect `of the electrical current. This is done by arranging a pair of' auxiliary thermostatic elements 64 in position so that Yllnderiz certain increase in temperature they will engage the sides of the main thermostat 42. The auxiliary thermostats are in the electrical circuit, so that when they engage the main thermostat part of the current is diverted through them and less current passes through the lower legs of the main thermostat. This operates to reduce the heating effect ofthe current onvthe main thermostat. A second pair of auxiliary thermostats 65 may be arranged to cut in after another defi-V ;Vnite rise in atmospheric temperature, and in a similar Way as many auxiliary thermostats as desired may be used, the thermostats being arranged to cut in atany desired steps of rise in atmospheric temperature.

I claim:

l1. A circuit breaker comprising a pair of contacts, a separating member adapted to separate the contacts, a first operating means to cause actuation of the separating member in response to light over-loads in the circuit, a second operating means to cause actuation of the separating member in response to heavy over-loads in the circuit, and means to short-circuit the first operating means in response to heavy overloads in the circuit.

2. Al circuit breaker comprising a pair of contacts, a separating member adapted to separate the contacts, thermostatic means to cause actuation of the separating member in response to light overloads in the circuit, a second operating means to cause actuation of the separating member in response to heavy over-loads in the circuit, and means to shortcircuit the thermostatic means in response to heavy overloads in the circuit.

3. A circuit breaker-comprising a pair of contacts, a separating member adapted to separate the contacts, actuating means for moving the separating member, a first operating means to initiate movement of the actuatmg means in response to light over-loads in the circuit, a second operating means to initiate movement ot' the actuating means in response to heavy over-loads in the circuit, and means to short-circuit the first operating means in response to heavy overloads in the circuit.

i. A circuit breaker comprising a pair of contacts, a separating member adapted to `separate the contacts, actuating means for moving the separating member, thermostatic means to initiate movement of the actuating means in response to light over-loads in the circuit, avsecond operating means to initiate movement or the actuating means in response to light over-loads in the circuit, a second operating means to release the latch in response to heavy over-loads in the circuit, and

means to short-circuit the first o erating means in response to heavy overloa s in the circuit.

6. A circuit breaker comprising a pair of contacts, an interposer adapted to extend between the contacts to interrupt the circuit, a spring normally biasing the interposer to in'- terrupting position, a latch for holding the interposer in inoperative position, thermostatic means to release the latch in response to li lit over-loads in the circuit, a second operatmg means to release the latch in response to heavy over-loads in the circuit, and means to short-'circuit the thermostatic means in response to heavy overloads in the circuit.

v7. A circuit breaker comprising a pair of contacts, aninterposer adapted to extend between the contacts to interrupt the circuit, a spring normally biasing the interposer to interrupting position, a latch for holding the interposer 1n inoperative position, thermostatic means to release'the latch in response to light over-loads in the circuit, electro-magnetic means to release the latch in response to heavy over-loads in the circuit, and electromagnetically controlled means to short-circuit the thermostatic means in response to heavy over-loads in the circuit.

8. A circuit breaker comprising a pair of contacts, a separating member adapted to separate the contacts, spring actuating means for moving the separating member, a latch for holding the interposer in inoperative position, manual means for releasing the latch, thermostatic means'to release the latch in response to light over-loads in the circuit, electro-magnetic means to release the latch in res nse to heavy over-loads in the circuit, and e cetro-magneticall controlled means to short-circuit the t ermostatic means in response to heavy over-loads in the circuit. Y

9. A circuit breaker comprising a pair of contacts, an interposer adapted to extend between the contacts to interrupt the circuit, a

quick acting spring normally biasing the interposer to interrupting position and for quickly and positively actuating the interser into interrupting position when released, a latch for holding the interposer in inoperative position against the tension of said spring, a first operating means to release the latch in response to light overloads in the circuit, and a second operating means to release the latch in response to heavy overloads in the circuit.

10. A circuit breaker comprising a casing having an insulating partition to form two independent contact chambers and having an opening therein, a first contact in .one of said contactchambers and extending through said opening, a second contact in the other of said contact chambers and for resiliently engaging said first contact, an insulating interposer adapted to extend between the contacts to interrupt the circuit and close the opening in said partition, a latch, for holding the interruptor in inoperative position, a first operating means to release the latch in response to light overloads in the circuit, and `a second operating means to release the latch in response to heavy overloads in the circuit.

11. A circuit breaker comprising a pair of Contact faces, one being stationary and the other s ring-pressed, a separating member adapte to operate and wipe said contact faces during separating action, a first operating means to cause actuation of the separating member in response to light overloads in the circuit, a second operating means to cause actuation of the separating member in response to heavy overloads in the circuit, and means to short-circuit the first o erating means in response to heavy overloa s in the circuit.

12. A/circuit breaker comprising a fixed extended contact face, a second Contact face, means for normally maintaining said second contact face in engagement with said fixed contact face, a separating member movable parallel to said fixed contact face to effectively wipe such contact face during operation, a first operatingmeans to cause actuation of the separatin member in response to light overloa ds in t e circuit, and a second operating means to cause actuation of the separating member in response to heavy overloads in the circuit. f

13. A circuit breaker comprising an insulating partition having an opening therein, a first contact extending through said opening, a second contact for resiliently engaging said first contact, an insulating interposerv adapted to extend between the contacts, close the opening in said partition and interrupt the circuit, a latch for holding the interruptor in inoperative position, thermostatic means to release the latch in response to light overloads in the circuit, a second operating means to release the latch in response to heavy overloads in the circuit, and means to shortcircuit the thermostatic means in response to heavy overloads in the circuit.

14. A circuit breaker comprising a fixed extended plane contact face, a second contact face, means for normally maintainin r said second contact face in engagement with said fixed contact face, a se arating'member movable parallel to sai fixed Contact face to effectively wipe such contact face during operation, a first operating means to cause actuation of the separating member in response to light overloads in the circuit, and a second operating means to cause actuation of the separating member in response tc heavy overloads in the circuit.

15. A circuit breaker comprising an insulating partition having an opening therein,

a first contact extending through said opening, a second contact for resiliently engaging said vfirst Contact, an insulating interposer adapted to extend between the contacts, close the opening in said partition and interrupt the circuit, a latch for holding the interruptor in inoperative position, thermostatic means to release the latch in response to an overload in the circuit, and a second operating means to release the latch in rcsponseto heavy overloads in the circuit.

In testimony whereof I alix my signature.

STEPHEN s. GRADY. 

